High performance stern drive

ABSTRACT

Disclosed herein is a marine propulsion installation including a hinge pin pivotally connecting a mounting bracket to a mounting plate for vertical swinging movement about a tilt axis, a King pin pivotally connecting a propulsion unit to the mounting bracket for common vertical swinging movement and for horizontal swinging movement therebetween about a steering axis, a first drive shaft rotatably supported by the mounting bracket about an axis extending perpendicularly to and vertically spaced from the tilt axis and perpendicularly to and in intersecting relation to the steering axis, a second drive shaft rotatably supported by the propulsion unit, an adjusting screw for adjustably vertically swinging the mounting bracket and the propulsion unit relative to the mounting plate through a limited range about the tilt axis, a universal joint extending across the steering axis and connecting the first and second drive shafts notwithstanding vertical swinging movement of the mounting bracket and the propulsion unit relative to the mounting plate and steering movement of the propulsion unit relative to the mounting bracket, an engine mounted in the boat hull and including an output shaft connected to the first drive shaft for common rotation therewith, by a telescopic drive shaft and a universal coupling, whereby to accommodate vertical swinging movement of the mounting bracket and the propulsion unit relative to the mounting plate.

United States Patent 1 [111 3,841,257 Stralig 1 Oct. 15, 1974 HIGH PERFORMANCE STERN DRIVE [57] ABSTRACT 115/18 R, 18 A, 26; 74/480 B; 114/144 R [56] References Cited UNITED STATES PATENTS 2,902,967 9/1959 Wanzer 115/35 R 2,969,763 1/1961 Foster 115/18 R 3,139,062 6/1964 Keefe 115/35 R 3,143,992 8/1964 Beams.... 115/26 3,202,125 8/1965 Morse.... 115/35 R 3,204,598 9/1965 Sharp 115/34 R 3,376,842 4/1968 Wynne l 115/35 R 3,403,655 10/1968 Warburton 115/41 R 3,404,656 10/1968 Chamberlain 115/41 R 3,422,780 1/1969 Becker et a1 115/41 R 3,478,620 ll/l969 Shimanckas 115/34 R 3,500,787 3/1970 Becker 115/41 R 3,570,443 3/1971 Dewhurst 115/41 R 3,577,954 5/1971 Borgersen 115/41 R 3,683,841 8/1972 Krautkremer 115/41 R Disclosed herein is a marine propulsion installation including a hinge pin pivotally connecting a mounting bracket to a mounting plate for vertical swinging movement about a tilt axis, a King pin pivotally connecting a propulsion unit to the mounting bracket for common vertical swinging movement and for horizontal swinging movement therebetween about a steering axis, a first drive shaft rotatably supported by the mounting bracket about an axis extending perpendicularly to and vertically spaced from the tilt axis and perpendicularly to and in intersecting relation to the steering axis, a second drive shaft rotatably supported by the propulsion unit, an adjusting screw for adjust ably vertically swinging the mounting bracket and the propulsion unit relative to the mounting plate through a limited range about the tilt axis, a universal joint extending across thesteering axis and connecting the first and second drive shafts notwithstanding vertical swinging movement of the mounting bracket and the propulsion unit relative to the mounting plate and steering movement of the propulsion unit relative to the mounting bracket, an engine mounted in the boat hull and including an output shaft connected to the first drive shaft for common rotation therewith, by a telescopic drive shaft and a universal coupling, whereby to accommodate vertical swinging movement of the mounting bracket and the propulsion unit relative to the mounting plate.

17 Clairns, 4 Drawing Figures HIGH PERFORMANCE STERN DRIVE BACKGROUND OF THE INVENTION Name Number Issue Date Griffith 1,780,075 October 28, 1930 Demichelis 2,064,l95 December 15, 1963 Hedges 2,114,633 April 19, 1938 Patty 2,936,730 May 17. 1960 Bergstedt 2,977,923 May 24, I961 MacDonald 3,368,516 February 13, 1968 MacDonald 3,368,517 February 13, 1968 Wynne 3,376,842 April 9, 1968 SUMMARY OF THE INVENTION The invention provides a stern drive unit wherein the trim or tilt axis is located forwardly of the steering axis, wherein the drive train extends in the propulsion unit rearwardly below the tilt axis and aft of the steering axis, wherein the propulsion unit can be trimmed through a limited range so as to obtain maximum boat performance, and wherein transmission of rotary power and steering control are continuously maintained notwithstanding trimming.

The invention also provides a marine propulsion installation including a stern drive unit such as that described in the immediately preceding paragraph, together with an engine which is substantially stationarily mounted in a boat hull and connected to a vertically swingable stern drive unit drive shaft by means including a telescopic universal joint located forwardly of the stern drive unit.

More particularly, the invention provides a marine propulsion installation including a stern drive unit comprising a mounting plate adapted for attachment to a boat transom or hull and having therein a central aperture, a mounting bracket pivotally connected to the mounting plate about a horizontal trim or tilt axis and including a forwardly projecting tubular portion extending through the mounting plate aperture and at least partially through an associated opening in the boat transom, and a propulsion unit connected to the vertically tiltable mounting bracket for common vertical swinging movement therewith and for steering movement relative thereto about a steering axis located aft of the tilt axis.

The propulsion unit includes a drive train operably connected between a propeller and a drive shaft which is supported in the propulsion unit for rotation about an axis extending generally fore and aft in a plane perpendicular to the steering axis. The drive shaft, in turn, is connected through a' universal joint or coupling aligned with the steering axis, to another drive shaft which is rotatably journaled in the tubular portion of the tiltable mounting bracket and which, in turn, is connected through a telescopic universal joint with the output shaft of an engine which is stationarily mounted in the boat hull. Also included are means for adjustably trimming the propulsion unit relative to the boat hull by adjustably pivoting or tilting the mounting bracket relative to the mounting plate without interrupting the transmission of rotary power from the engine to the propeller, together with a parallel linkage steering control which is continuously operable notwithstanding adjustment of the trim condition of the propulsion unit.

One of the principal objects of the invention is the provision of a stern drive unit which is particularly adapted for racing and which includes a propulsion unit which is adjustably pivotable about a horizontal axis through a limited range to afford trimming of the propulsion unit relative to the boat hull and thereby to obtain maximum boat performance, without permitting such tilting of the propulsion unit through a full tilt range so as to remove the propeller from the water.

Another one of the principal objects of the invention is the provision of a high performance stern drive unit which is designed for simplicity, strength, minimum weight and low cost.

Another of the principal objects of the invention is the provision of a stern drive unit affording trimming of the propulsion unit under way so as to afford maximum boat performance and without interrupting continuous transmission of rotary power to the propeller and propulsion unit steering control.

Other objects and advantages of the invention will become known with reference to the following description, claims and drawings.

THE DRAWINGS FIG. 1 is a somewhat schematic side elevational view, partially in section, of a marine propulsion installation embodying various of the features of the invention.

FIG. 2 is an enlarged view, in section, of various of the components illustrated in FIG. 1.

FIG. 3 is a fragmentary view taken along line 33 of FIG. 2, with parts omitted.

FIG. 4 is a fragmentary view, taken along line 44 of FIG. 2, with parts omitted.

GENERAL DESCRIPTION Shown in FIG. 1 of the drawings is a marine propulsion installation or device 11 which includes any suitable intrnal combustion engine 13 stationarily mounted in a boat hull 15 by suitable means illustrated at 17, together with a stern drive unit 19 which is mounted to the boat hull l5, and particularly to the boat transom 21, and power transmission means 23 connecting the engine output shaft 25 to the stern drive unit 19.

The stem drive unit 19 is more fully illustrated in FIG. 2 and includes a mounting bracket or plate 31 which can be suitably fixed or attached to the boat transom 21 and which includes a central aperture 33, together with a horizontally spaced, aligned pair of pi]- low blocks 35 located above the central aperture 33, and an enlarged portion 37 adapted to pivotally mount a tiller 39 as will hereinafter be disclosed in greater detail. If desired, as shown in FIG. 3, the mounting plate 31 can also include, at the lower end thereof, two spaced abutments 41 to provide additional stability to a mounting bracket 43 which is pivotally carried from the mounting plate 31 for limited vertical swinging movement on a horizontal tilt axis 40 extending through the pillow blocks 35.

More particularly, the mounting bracket 43 is generally of triangular shape, as shown in FIG. 3, and includes a relatively narrow lower portion extending between the abutments 41 and a relatively enlarged upper portion extending between the pillow blocks 35. Also included in the mounting bracket 43 are vertically spaced upper and lower pillow blocks 45 which provide a steering axis 49 for a propulsion or drive unit 51 still to be described. The steering axis 49 extends perpendicularly to the horizontal tilt axis 40 in a generally vertical direction and is located in spaced relation from, and aft of, the horizontal tilt axis 40.

Adjacent its relatively enlarged upper end, the mounting bracket 43 includes a pair of horizontally extending stub shafts 47 which are rotatably received in the pillow blocks 35 of the mounting plate 31 to provide for vertical swinging movement of the mounting bracket 43 relative to the mounting plate 31.

Also included in the mounting bracket 43 is a central aperture 53 and a forwardly projecting tubular portion 57 which extends from the aperture 53 and projects through the aperture 33 in the mounting plate 31 and at least partially through an opening in the boat transom 21. The outer diameter of the tubular portion 57 is smaller than the aperture 33 in the mounting plate 31 so as to accommodate limited vertical swinging movement of the mounting bracket 43 about the horizontal tilt axis 40 relative to the mounting plate 31 and boat hull 15. A flexible rubber boot or seal 58 extends between the mounting plate 31 and the tubular portion 57 to exclude moisture.

The propulsion unit 51 includes two vertically spaced and aligned apertures 61 which receive respective stub shafts or king pins 63 extending through the mounting bracket pillow blocks 45 so as to afford horizontal swinging movement or steering of the propulsion unit 51 about the steering axis 49 relative to the mounting bracket 43 and boat hull 15, while also affording common vertical swinging movment with the mounting bracket 43 about the horizontal axis 40 and relative to the mounting plate 31 and boat hull 15.

Rotatably supported by bearings 55 carried in the propulsion unit 51 is a drive shaft 67 which extends generally in the fore and aft direction and in generally perpendicular relation to the steering axis 49.

The drive shaft 67 forms part of a suitable drive train 69 which connects the drive shaft 67 to a propeller shaft 71 which is rotatably mounted in the propulsion unit 51 and carries a propeller 73. if desired, the drive train 69 can include a reversing transmission (not shown) either on the drive shaft 67 or on the propeller shaft 71 or elsewhere in the drive train 69. Preferably, the drive train 69 is designed to permit maximum transmission of power while minimizing the horizontal cross sectional area of that portion of the propulsion unit 51 which is normally immersed in water during operation.

Rotatably supported by bearings 81 mounted in the tubular portion 57 of the mounting bracket 43 is another drive shaft 83 which extends generally in the fore and aft direction, and in perpendicular relation to the steering axis 49, and in co-planar relation to the drive shaft 67, and in vertically spaced relation to the horizontal tilt axis 40. As illustrated in FIG. 2, the drive shaft 83 extends in spaced relation below the horizontal tilt axis 40.

Means are provided for drivingly connecting the rearward end of the drive shaft 83 to the forward end of the drive shaft 67 for rotary power transmission, notwithstanding steering movement of the propulsion unit 51 relative to the mounting bracket 43. Various arrangements can be employed. The illustrated construction employs a universal coupling in the form of an intermediate stub shaft 84 and two U joint pivotal connections 85 and 87 which connect the stub shaft 84 to the drive shafts 67 and 83 and which are arranged with their respective pivotal axes at right angles to each other.

In order to protect the universal coupling from moisture as well as to prevent entry of moisture into the drive train 67 and into the tubular portion 57 of the mounting bracket 43, a flexible, hollow bellows 91 extends around the universal coupling from oppositely lips or flanges 93 and 95 located respectively on the mounting bracket 43 and on the propulsion unit 51.

The before mentioned power transmission means 23 connects the engine output shaft 25 to the forward end of the drive shaft 83 which is vertically swingable in accordance with the vertical swinging movement of the mounting bracket 43. While other constructions could be employed, in the illustrated construction, the power transmission means 23 comprises a telescopic drive shaft 101 including two telescopically movable members (not shown) subject to common rotation. In addition, the engine output shaft 25 is connected to the for ward end of the telescopic shaft 101 by U joint pivotal connection 103 while the rear of the telescopic shaft 101 is connected to the forward end of the drive shaft 83 by a second U joint pivotal connection 105 arranged with its pivot axis at a right angle with respect to the pivot axis of the U joint connection 103. As a consequence, the power transmission means 23 constitutes, in effect, a telescopic universal coupling which accommodates vertical swinging movement of the drive shaft 83 relative to the engine output shaft 25, while permitting continuous transmission of rotary power.

In further accordance with the invention, there is provided means for tilting or trimming the propulsion unit 51 relative to the mounting plate 31 or boat hull 15 through a limited range so as to afford maximum propulsive effect. Various hydraulic or mechanical or other arrangements can be employed. In the illustrated construction, there is provided a pivotal connection of adjustable length between the mounting bracket 43 and the mounting plate 31. More specifically, each of the mounting plate 31 and mounting bracket 43 are provided, below the respective apertures 33 and 53, with facing, partially spherical sockets 103 and 105 respectively receiving ball members 107 and 109 which are diametrically bored and oppositely threaded. The ball members 107 and 109 are connected by a crank 111 having threaded portions received in the threaded bores of the ball members 107 and 109 such that rotatable crank movement is effective, within a limited range, i.e., less than about 30, to trim the propulsion unit 51 relative to the boat hull 15, while the boat is under way and without affecting transmission of rotary power from the engine 13 to the propeller 71.

In still further accordance with the invention, the marine propulsion device or installation 11 includes a propulsion unit steering control means in the form of the before mentioned tiller 39 which is pivotally mounted on the enlarged portion 37 of the mounting plate 31 and which extends inwardly of the boat hull forwardly of the transom 21, together with a linkage 121 connecting the tiller 39 to the propulsion unit 51. While various other arrangements could be employed, in the illustrated construction, the tiller 39 is pivotally mounted on the mounting plate 31 about a tiller axis 122 which extends vertically and in fore and aft alignment with the steering axis 49 and which can intersect the horizontal tilt axis 40.

The linkage 121 includes a first steering arm 123 which extends fixedly from the tiller 39 and a second steering arm 125 which extends fixedly from the propulsion unit 51. In addition, the linkage 121 includes a connecting link 127, and means respectively pivotally connecting the opposite ends of the connecting link 127 to the first and second steering arm 123 and 125. When the steering axis 49 is vertical, i.ev parallel to the tiller axis 122, the arrangement is such that the steering arms 123 and 125 (relative to the appropriate axes at each end) are of equal length and extend in general parallel relation to each other, and such that the connecting link 127 extends in the fore and aft direction and has a length (between its pivotal connections) substantially equal to the fore and aft distance between the tiller axis 122 and the steering axis 49. Thus there is provided a parallel linkage which is operative to steer the propulsion unit 51 in proportion to the steering movement applied to the tiller 39.

In order to accommodate the permissable limited vertical swinging movement of the propulsion unit 51 relative to the mounting plate 31, the means pivotally connecting the steering arms 123 and 125 to the ends of the connecting link 127 each afford pivotal movement about two axes at right angles to each other. More specifically, the pivotal connection between the tiller steering arm 123 and the forward end of the connecting link 127 is provided by a U joint pivotal connection 131 providing a vertical axis to afford horizontal swinging movement and including a somewhat oversized aperture 133 in the associated end of the connecting link 127, whereby to afford vertical swinging movement of the connecting link 127 relative to the tiller 39 as seen generally in FIG. 2. The pivotal connection between the rearward end of the connecting link 127 and the propulsion unit steering arm 125 is a ball and socket connection 137.

The disclosed marine propulsion installation 11 is particularly adapted for use in racing events and permits limited tilting of the propulsion unit 51 relative to the boat hull 15 so as to optimize the propulsive efi'ect of the rotating propeller 71, while affording continuous steering control and continuous transmission of rotary power from the engine 13 to the propeller 71. In addition, the disclosed construction is relatively economic to build and maintain, and combines the advantages of low weight and structural strength.

Various of features of the invention are set forth in the following claims.

I claim:

1. A marine propulsion device comprising a mounting plate adapted to be fixed to the hull of a boat, a mounting bracket, means pivotally connecting said mounting bracket to said mounting plate for vertical swinging movement about an axis which is approximately horizontal when said mounting plate is attached to the boat hull, a propulsion unit including a rotatably mounted propeller, means pivotally connecting said propulsion unit to said mounting bracket for common vertical swinging movement of said propulsion unit with said mounting bracket and for steering movement of said propulsion unit relative to said mounting bracket about a steering axis extending rearwardly of said horizontal axis, a first drive shaft supported by said mounting bracket for rotation about an axis extending perpendicularly to and vertically spaced from said horizontal axis and perpendicularly to and in intersecting relation to said steering axis, a second drive shaft drivingly connected to said propeller and supported by said propulsion unit for rotation about an axis perpendicular to said steering axis and co -planar with the axis of said first drive shaft, means for adjustably vertically swinging said mounting bracket and said propulsion unit relative to said mounting plate through a limited range about said horizontal axis, and a universal joint extending across said steering axis and connecting said first and second drive shafts notwithstanding vertical swinging movement of said mounting bracket and said propulsion unit relative to said mounting plate and steering movement of said propulsion unit relative to said mounting bracket.

2. A marine propulsion device in accordance with claim 1 wherein said first drive shaft is vertically spaced below said horizontal axis.

3. A marine propulsion device in accordance with claim 1 and further including a watertight flexible bellows surrounding said universal joint and extending between said mounting bracket and said propulsion unit.

4. A marine propulsion device in accordance with claim 1 wherein said mounting plate includes therein an aperture, and wherein said mounting bracket includes a forwardly projecting tubular portion extending in said aperture, and further including flexible sealing means extending between said mounting plate and said tubular portion.

5. A marine propulsion device in accordance with claim 4 and further including a pair of spaced bearings supported within said tubular portion and journaling said first drive shaft.

6. A marine propulsion device in accordance with claim 1 and further including an engine mounted in said boat hull and including an output shaft, and means connecting said output shaft and said first drive shaft for common rotation and including telescopic drive means and universal coupling means, whereby to accommodate vertical swinging movement of said mounting bracket and said propulsion unit relative to said mounting plate.

7. A marine propulsion device in accordance with claim 1 and further including a tiller supported by said mounting plate for pivotal movement about a generally vertical tiller axis, and means connecting said tiller to said propulsion unit for steering said propulsion unit in response to tiller movement, notwithstanding vertical swinging movement of said propulsion unit relative to said mounting plate.

8. A marine propulsion device in accordance with claim 7 wherein said means connecting said tiller to said propulsion unit includes a first steering arm extending fixedly from said tiller for common movement therewith, a second steering arm extending fixedly from said propulsion unit, a steering link, and means pivotally connecting said steering link to said first and second steering arms.

9. A marine propulsion device in accordance with claim 8 wherein said first and second arms are substantially parallel when said tiller axis and said steering axis are parallel.

10. A marine propulsion device in accordance with claim 8 wherein said tiller axis is aligned fore and aft with said steering axis and wherein said link has a length substantially equal to the fore and aft distance between said tiller axis and said steering axis when said tiller axis and said steering axis are parallel.

11. A marine propulsion device in accordance with claim 8 wherein said tiller axis is aligned fore and aft with said steering axis and wherein said first and second arms have substantially the same length and are substantially parallel when said tiller axis and said steering axis are parallel and wherein said link has a length substantially equal to the fore and aft distance between said tiller axis and said steering axis when said tiller axis and said steering axis are parallel.

12. A marine propulsion device in accordance with claim 11 wherein said means pivotally connecting said steering link to said first and second steering arms provides pivotal movement of said link relative to each of said first and second steering arms about two axes at right angles to each other to accommodate vertical swinging movement of said steering axis relative to said tiller axis.

13. A marine propulsion device comprising a mounting plate adapted to be fixed to the hull of a boat, a mounting bracket, means pivotally connecting said mounting bracket to said mounting plate for vertical swinging movement about a tilt axis which is approximately horizontal when said mounting plate is attached to the boat hull, a propulsion unit, means pivotally connecting said propulsion unit to said mounting bracket for common vertical swinging movement of said propulsion unit with said mounting bracket and for steering movement of said propulsion unit relative to said mounting bracket about a steering axis extending rearwardly of said tilt axis and transversely thereof, a tiller supported by said mounting plate for pivotal movement about a tiller axis extending in generally parallel relation to and in fore and aft alignment with said steering axis, a first steering arm extending fixedly from said tiller for common movement therewith, a second steering arm extending fixedly from said propulsion unit, a steering link having a length substantially equal to the fore and aft distance between said tiller axis and said steering axis, and means pivotally connecting said steering link to said first and second steering arms.

14. A marine propulsion device in accordance with claim 13 wherein said first and second arms are substantially parallel.

15. A marine propulsion device comprising a mounting plate adapted to be fixed to the hull of a boat, a mounting bracket, means pivotally connecting said mounting bracket to said mounting plate for vertical swinging movement about a tilt axis which is approximately horizontal when said mounting plate is attached to the boat hull, a propulsion unit, means pivotally connecting said propulsion unit to said mounting bracket for common vertical swinging movement of said propulsion unit with said mounting bracket and for steering movement of said propulsion unit relative to said mounting bracket about a steering axis extending rearwardly and transversely of said tilt axis, a tiller sup ported by said mounting plate for pivotal movement about a tiller axis extending substantially parallel to and in fore and aft alignment with said steering axis, a first steering arm extending rigidly from said tiller for common movement therewith, a second steering arm extending rigidly from said propulsion unit, said first and second arms having substantially the same length and being substantially parallel, a steering link having a length substantially equal to the fore and aftdistance between said tiller axis and said steering axis and means pivotally connecting said steering link to said first and second steering arms.

16. A marine propulsion device in accordance with claim 15 wherein said means pivotally connecting said steering link to said first and second steering arms provides pivotal movement of said linkrelative to each of said first and second steering arms about two axes at right angles to each other to accommodate vertical swinging movement of said steering axis relative to said tiller axis.

17. A marine propulsion device comprising a mounting plate adapted to be fixed to the hull of a boat, a mounting bracket, means pivotally connecting said mounting bracket to said mounting plate for vertical swinging movement about an axis which is approxi* mately horizontal when said mounting plate is attached to the boat hull, a propulsion unit including a rotatably mounted propeller, means pivotally connecting said propulsion unit to said mounting bracket for common vertical swinging movement of said propulsion unit with said mounting bracket and for steering movement of said propulsion unit relative to said mounting bracket about a steering axis extending rearwardly of said horizontal axis, a first drive shaft supported by said mounting bracket for rotation about an axis extending fore and aft, a second drive shaft drivingly connected to said propeller and supported by said propulsion unit for rotation about an axis extending fore and aft, and a universal joint connecting said first and second drive shafts notwithstanding vertical swinging movement of said mounting bracket and said propulsion unit relative to said mounting plate and steering movement of said propulsion unit relative to said mounting bracket. 

1. A marine propulsion device comprising a mounting plate adapted to be fixed to the hull of a boat, a mounting bracket, means pivotally connecting said mounting bracket to said mounting plate for vertical swinging movement about an axis which is approximately horizontal when said mounting plate is attached to the boat hull, a propulsion unit including a rotatably mounted propeller, means pivotally connecting said propulsion unit to said mounting bracket for common vertical swinging movement of said propulsion unit with said mounting bracket and for steering movement of said propulsion unit relative to said mounting bracket about a steering axis extending rearwardly of said horizontal axis, a first drive shaft supported by said mounting bracket for rotation about an axis extending perpendicularly to and vertically spaced from said horizontal axis and perpendicularly to and in intersecting relation to said steering axis, a second drive shaft drivingly connected to said propeller and supported by said propulsion unit for rotation about an axis perpendicular to said steering axis and co-planar with the axis of said first drive shaft, means for adjustably vertically swinging said mounting bracket and said propulsion unit relative to said mounting plAte through a limited range about said horizontal axis, and a universal joint extending across said steering axis and connecting said first and second drive shafts notwithstanding vertical swinging movement of said mounting bracket and said propulsion unit relative to said mounting plate and steering movement of said propulsion unit relative to said mounting bracket.
 2. A marine propulsion device in accordance with claim 1 wherein said first drive shaft is vertically spaced below said horizontal axis.
 3. A marine propulsion device in accordance with claim 1 and further including a watertight flexible bellows surrounding said universal joint and extending between said mounting bracket and said propulsion unit.
 4. A marine propulsion device in accordance with claim 1 wherein said mounting plate includes therein an aperture, and wherein said mounting bracket includes a forwardly projecting tubular portion extending in said aperture, and further including flexible sealing means extending between said mounting plate and said tubular portion.
 5. A marine propulsion device in accordance with claim 4 and further including a pair of spaced bearings supported within said tubular portion and journaling said first drive shaft.
 6. A marine propulsion device in accordance with claim 1 and further including an engine mounted in said boat hull and including an output shaft, and means connecting said output shaft and said first drive shaft for common rotation and including telescopic drive means and universal coupling means, whereby to accommodate vertical swinging movement of said mounting bracket and said propulsion unit relative to said mounting plate.
 7. A marine propulsion device in accordance with claim 1 and further including a tiller supported by said mounting plate for pivotal movement about a generally vertical tiller axis, and means connecting said tiller to said propulsion unit for steering said propulsion unit in response to tiller movement, notwithstanding vertical swinging movement of said propulsion unit relative to said mounting plate.
 8. A marine propulsion device in accordance with claim 7 wherein said means connecting said tiller to said propulsion unit includes a first steering arm extending fixedly from said tiller for common movement therewith, a second steering arm extending fixedly from said propulsion unit, a steering link, and means pivotally connecting said steering link to said first and second steering arms.
 9. A marine propulsion device in accordance with claim 8 wherein said first and second arms are substantially parallel when said tiller axis and said steering axis are parallel.
 10. A marine propulsion device in accordance with claim 8 wherein said tiller axis is aligned fore and aft with said steering axis and wherein said link has a length substantially equal to the fore and aft distance between said tiller axis and said steering axis when said tiller axis and said steering axis are parallel.
 11. A marine propulsion device in accordance with claim 8 wherein said tiller axis is aligned fore and aft with said steering axis and wherein said first and second arms have substantially the same length and are substantially parallel when said tiller axis and said steering axis are parallel and wherein said link has a length substantially equal to the fore and aft distance between said tiller axis and said steering axis when said tiller axis and said steering axis are parallel.
 12. A marine propulsion device in accordance with claim 11 wherein said means pivotally connecting said steering link to said first and second steering arms provides pivotal movement of said link relative to each of said first and second steering arms about two axes at right angles to each other to accommodate vertical swinging movement of said steering axis relative to said tiller axis.
 13. A marine propulsion device comprising a mounting plate adapted to be fixed to the hull of a boat, a mounting bracket, means pivotally connecting said mounting brAcket to said mounting plate for vertical swinging movement about a tilt axis which is approximately horizontal when said mounting plate is attached to the boat hull, a propulsion unit, means pivotally connecting said propulsion unit to said mounting bracket for common vertical swinging movement of said propulsion unit with said mounting bracket and for steering movement of said propulsion unit relative to said mounting bracket about a steering axis extending rearwardly of said tilt axis and transversely thereof, a tiller supported by said mounting plate for pivotal movement about a tiller axis extending in generally parallel relation to and in fore and aft alignment with said steering axis, a first steering arm extending fixedly from said tiller for common movement therewith, a second steering arm extending fixedly from said propulsion unit, a steering link having a length substantially equal to the fore and aft distance between said tiller axis and said steering axis, and means pivotally connecting said steering link to said first and second steering arms.
 14. A marine propulsion device in accordance with claim 13 wherein said first and second arms are substantially parallel.
 15. A marine propulsion device comprising a mounting plate adapted to be fixed to the hull of a boat, a mounting bracket, means pivotally connecting said mounting bracket to said mounting plate for vertical swinging movement about a tilt axis which is approximately horizontal when said mounting plate is attached to the boat hull, a propulsion unit, means pivotally connecting said propulsion unit to said mounting bracket for common vertical swinging movement of said propulsion unit with said mounting bracket and for steering movement of said propulsion unit relative to said mounting bracket about a steering axis extending rearwardly and transversely of said tilt axis, a tiller supported by said mounting plate for pivotal movement about a tiller axis extending substantially parallel to and in fore and aft alignment with said steering axis, a first steering arm extending rigidly from said tiller for common movement therewith, a second steering arm extending rigidly from said propulsion unit, said first and second arms having substantially the same length and being substantially parallel, a steering link having a length substantially equal to the fore and aft distance between said tiller axis and said steering axis and means pivotally connecting said steering link to said first and second steering arms.
 16. A marine propulsion device in accordance with claim 15 wherein said means pivotally connecting said steering link to said first and second steering arms provides pivotal movement of said link relative to each of said first and second steering arms about two axes at right angles to each other to accommodate vertical swinging movement of said steering axis relative to said tiller axis.
 17. A marine propulsion device comprising a mounting plate adapted to be fixed to the hull of a boat, a mounting bracket, means pivotally connecting said mounting bracket to said mounting plate for vertical swinging movement about an axis which is approximately horizontal when said mounting plate is attached to the boat hull, a propulsion unit including a rotatably mounted propeller, means pivotally connecting said propulsion unit to said mounting bracket for common vertical swinging movement of said propulsion unit with said mounting bracket and for steering movement of said propulsion unit relative to said mounting bracket about a steering axis extending rearwardly of said horizontal axis, a first drive shaft supported by said mounting bracket for rotation about an axis extending fore and aft, a second drive shaft drivingly connected to said propeller and supported by said propulsion unit for rotation about an axis extending fore and aft, and a universal joint connecting said first and second drive shafts notwithstanding vertical swinging movement of said mounting bracket and said propulsion unit relatIve to said mounting plate and steering movement of said propulsion unit relative to said mounting bracket. 